PHOENIX — Flooding from heavy monsoon season rains in the Phoenix area forced authorities on Tuesday to close several major roads, including a portion of Interstate 17, while elsewhere firefighters rescued multiple motorists and a small trailer park was evacuated.

The National Weather Service issued a flash flood warning for much of the metro area and north of the city where up to 8 inches of rain has fallen in some of the mountainous regions along the interstate.

The storms are expected to affect a large area of the state throughout the day.

“It’s like a conveyor belt of showers coming through here,” National Weather Service meteorologist Ken Waters said. “We’re seeing new cells popping up in the Phoenix area and just outside the Phoenix area.”

Sporadic storms are expected to continue in the area for the next few days.

“There’s a lot of concern about flash flooding,” Waters said.

Dramatic aerial television footage showed a river of muddy water rushing down I-17 about 25 miles north of Phoenix as motorists worked to move into other lanes to avoid the deluge. Another scene showed authorities pulling an elderly woman from a van stuck in fast-moving floodwaters that quickly began to engulf the vehicle.

The Arizona Department of Public Safety has since closed a roughly 15-mile stretch of I-17 and is redirecting traffic into the southbound lanes back toward Phoenix.

Officials said it’s unclear when the highway will reopen, and Waters expects several more inches of rain in the area over the next few hours.

The Arizona Department of Transportation will have to clear the road of mud and debris when the floodwaters recede to allow authorities to reopen one lane at a time hopefully by the afternoon, DPS spokesman Bart Graves said.

“Earlier we were very concerned that it was moving so fast that it would take over I-17 completely both northbound and southbound,” Graves said. “But it didn’t, so now ADOT is going to have to sweep that water out of there, which is going to be a long, arduous project.”

Rocks also washed down a hillside onto I-17 about 60 miles north of Phoenix, causing several vehicle collisions, but no deaths or major injuries have been reported, Graves said.

Meanwhile, residents of a small trailer park in Black Canyon City along a river about 40 miles north of Phoenix were evacuated late Tuesday morning, according to the Yavapai County Sheriff’s Office.

There had so far been minimal flooding damage to the park, but authorities wanted to get residents to a safe location because water has damaged roads in the vicinity, sheriff’s spokesman Dwight D’Evelyn said.